Electrical heating device



, July 2, 1946. E. R. ZI EGLER I ELECTRICAL HEATING DEVICE 3 Sheets-Sheet 1 Filed Sept 16', 1944 INVENfOR. @6726422133 .527

July 2, 1946.

E. R. ZIEGLER v ELECTRICAL HEATING DEVICE 5 Sheets-Sheet 2 Filed Sept. 16, 1944 INVENTOR.

13296226122 [eager B Y 1&7}? 1946 E. R. ZIEGLER ELECTRICAL HEATING DEVICE Filed Sept. 16, 1944 E'Shets-Sheet 5 INVENIOR; 622263327" $5- Agar/Z Patented July 2, 1946 ELECTRICAL HEATING DEVICE Eugene R. Ziegler, Spencerport, N. Y., assignor to Bitter Company, Inc., Rochester, N. Y., acorporation of Delaware Application September 16, 1944', Serial No. 554,394

9 Claims.

1 This invention relates to electrical heating devices, and, more particularly, to those of smaller Fig. 8 is an enlarged View similar to Fig. 4, but in a plane at right angles thereto;

size adapted to be quickly and conveniently en- Fig. 9 is a view substantially on the line 9a9a ergized for heating instruments and materials, in Fig. 8, and

such as employed, for example, in the practice of Fig. 10 is a top plan View of the intermediate the dental and medical professions. section of the base shown in Fig. 7.

One object of the invention is to provide an The embodiment of the invention herein disimproved device of the above character of a closed by way of illustration, is one adapted for more efficient, economical and convenient nature. use in place of the Bunsen burner or other gas Another object is to provide such a device 10 heater commonly provided on the known stands adapted for use instead of the Bunsen burner employed in the dental and medical fields for heretofore commonly employed by practitioners supporting a variety of equipment within conin the dental and medical professions. venient reach of the operator.

Another object is to provide a heating device Referring more particularly to Fig. 1, there is of the nature indicated comprising an electrical shown at l5 the branching arm of a dental equipheating element adapted to be quickly energized ment stand, having pivoted thereon at US a and to rapidly produce an intense heat. swinging arm IT, on the outer free end [8 of A further object is to provide such a device which is pivotally mounted a sleeve-like hub l9, capable of being conveniently and economically oia second swinging arm 20, on which is mountenergized as, for example, by the mere pressure ed the usual instrument table 2|. In this known thereagainst of an instrument to be heated, durtype of construction, a Bunsen burner has been ing the heating period only. commonly incorporated in the vertical pivotal Still a further object is to afford such a device axis of said hub I9, conveniently close to the inprovided with means for completely protecting strument table. In accordance with the present the operator, as well as the operating parts invention, an electrical heating device is located against injury. in the same advantageous position, on the ver- Still a further object is the provision of a detical pivotal axis of the outer arm close to the vice such as described in a construction capable table, as shown in Fig. l, and hereafter described. of being readily and economically manufactured Referring to Fig. 4, the sleeve-like hub IS on and assembled and of being readily taken apart the table arm is journaled on a hollow, vertical for cleaning and reassembled in use. trunnion 22, extending upwardly from the end of To these and other ends the invention resides arm ll, a screw 23 in the hub having its inner in certain improvements and combinations of end loosely engaged. in a groove 24 in the trunnion parts, all as will be hereinafter more fully deto-prevent inadvertent removal. Arm 20 has its scribed, the novel features being pointed out in intermediate portion enlarged to form a box-like the claims at the end of the specification. casing 2 5, for a transformer 26, which may be of In the drawings: any known and suitable type, such, for example,

Fig. 1 is a side elevation of a device embodying as commonly employed with neon signs to furthe present invention and illustrating the same nish high voltage current. Hub l9 has an openas applied to a dental equipment stand; ing 21., for the passage of conductors to and from Fig. 2 is a top plan view of the device shown the transformer and the hub has an upwardly in Fig. 1, but detached from the equipment stand; extended, open end 28, for supporting the heating Fig. 3 is an enlarged, sectional elevation of device proper, which will now be described. parts of the device in associationwith a diagram The heating device comprises, preferably, a of the electrical connections; generally cylindrical base portion, formed in sev- Fig. 4 is an enlarged, sectional elevation of the eral separable sections, mounted on the upper device with portions broken away a d Showing end of the hub and provided at its upper end the parts in inactive position; with a heating element enclosed within one or Fig. 5 is a view similar to Fig. 4, but showing more housing shells, through the open top of the parts in energizing position; 0 which the heat is applied to the article to be Fig. 6 is a section on the line Got-45a in Fig. 5, heated. showing the energizing switch and means for The base preferably comprises three superoperating the same; posed sections, 29, 30 and 3|, of rubber, plastic,

Fig. I is a side elevation showing the intermedior other known or suitable moldable, insulating ate section of the base of the device detached; 6!! material. Section 29 rests on the upper end of hub I9, to which it is secured by screws, as hereafter described. This section is hollowed out in an irregular shape, to receive the switch 32 and the switch actuating frame or spider 33, which will be more fully described hereafter. Section 29 has molded therein spaced high tension conductors, 34 and 35, extending longitudinally therethrough at opposite sides and having their ends projecting above the section and provided with connecting plug ends, 36 and 31.

The intermediate section 30 of the base comprises a body portion 38, Fig. 7, having depending opposite skirts 39, overlying the sides of the bottom section 29 opposite the high tension conductors 34 and 35, to increase the protection against outward sparking between the meeting faces of the adjacent sections. Molded in section 38 are conducting sockets, 40 and 4|, Figs. 4 and 5, engaging the conducting plugs 36 and 31 of the high tension conductors, each plug and its socket being preferably formed with a coacting ridge or groove, as shown at 42, to frictionally hold the sections together. The sockets 40 and 4| are fixed to socket sleeves, 43 and 44, extending upwardly above the ends of bosses, 45 and 46, formed on the top end of the section 39, as shown.

The upper base section 3| is of generally plate shape with its bottom face formed with recesses receiving the tapered upper ends of the bosses 45 and 46, which are adapted to wedge in the recesses and frictionally hold the parts together. The bottom face 41 of section 3| abuts upon shoulders, 48 and 49, of bosses 45 and 46, so as to be retained in spaced relation above the upper face 50 of portion 38 of the intermediate section 30, to preserve an air duct between the sections, for the purpose hereafter described. The bottoms of the recesses in the lower face of section 3| are further recessed to receive the upper ends of the conducting sleeves 43 and 44, and have molded therein a pair of conducting plugs, 52 and 53, the lower ends of which are slotted for resiliency, and frictionally and detachably engaged in the said sleeves. Plugs 52 and 53 are fixed at their upper ends to the outwardly bent ends of a pair of spaced, metal strip electrodes, 54 and 55 diverging upwardly above the base for supporting thereacross a high voltage arc. These electrodes are made of any known and suitable material adapted to resist burning by the arc.

It is evident from the above description that the base comprises the three sections, 29, 30 and 3|, which, with their respective conducting portions, are detachably connected together, with the high voltage connections extending continuously through the sections, when assembled, from top to bottom of the base. The intermediate section 30 is more positively secured to the bottom section 29, and both sections to the hub I9, by means of oppositely disposed screws, 56 and 51, Fig. 8, which are passed through the portion 38 of the middle section 30, through the lower section 29, and screwed into threaded holes in the bosses formed on the walls of the hub |9. On removal of the upper section 3|, however, these screws may be removed and the sections 29 and 30 separated and detached, when necessary.

A housing is provided for the electrodes 54 and 55, comprising an inner refractory shell 58 and an outer metal shell 59, Figs. 4, 5 and 8, havin the general shape of a truncated cone and spaced from each other, as shown. Inner shell 58 is preferably seated and supported at its lower edge in a recess in the top face of the base and protected by asbestos facing strips, 60 and 6|. These shells may be made of other materials, if desired, those mentioned having been found highly sat isfactory for the purpose.

For transmitting upwardly the heat generated by the electric arc, inner shell 58 has an upper opening 62, preferably in its top surface, above the electrodes, and the outer shell 59 has a similar registering opening 63 formed in an inwardly turned top flange 64 at its top.

Outer shell 59 of the housing is movably supported on the base, preferably by connection with means for actuating the switch controlling the electric circuit, so that downward pressure on the top of the outer shell serves to actuate the switch. To this end, the side walls of the outer shell are fixed by means of short screws 65, Figs. 6 and 9, to the outer ends 66 of the arms of a frame or spider 33, movably housed in the hollow lower section 29 of the base. The spider is preferably made of rubber, plastic, or other known or suitable plastic material, and has molded in its upper face a pin 68, sliding loosely in a socket in the middle section 30, to guide the spider for a short vertical movement. The lower face 69 of the spider, Fig. 8, is arranged to bear against an actuating button 70 in the top of the casing of the spring actuated switch 32, the button normally occupying an upper position corresponding to the open position of the switch and the inactive position of the heater. The switch is preferably of the type known commercially as a Switchette, manufactured and sold by the General Electric Company, and having the construction hereafter described, The switch spring has suflicient strength to normally hold the spider 33 and the outer shell 59 in the upper position of the latter, shown in Figs. 4 and 8, and the shell may be pressed downwardl on the switch button and move the switch to closed position, the parts then having the position shown in Fig. 5, with the flange 64 of the outer shell coming to rest against the top of the inner shell 58.

The said switch comprises opposite pairs of spaced contacts 'H and 12, Fig. 8, and a resilient conducting plate 13 has its opposite ends provided with contacts 12a playing between the pairs of contacts, 1| and 12, respectively. Plate 13 is cut and formed to provide upwardly inclined, resilient portions 14, engaged by spring fingers 15, depending from the button Ill, so as to normally hold the button elevated and the plate contacts 12a in engagement with the lower contacts 12 which in this instance are not connected in circuit. When the button is depressed, however, plate portions 14 are depressed, with the result that the stability of shape of the plate is overcome and its ends snap upwardly and engage and electrically connect the terminals 1| connected in the circuit of the device, so as to close the circuit and energize the heating element. Upon release of the pressure on outer shell 59, however, plate 13 springs back into normal shape so that its ends lie against the lower terminal 12, and its portions 14 raise the button, the spider and the shell to upper, inactive position in which the circuit it broken between the contacts I.

Switch 33 has terminals 16, Fig. 6, connected in series in one of the conductors l1 connecting the low voltage side of the transformer with the service power line, as shown in the circuit diagram, Fig. 3. Any other known or suitable spring actuated switch may be employed, of course, but I have found the commercially available switch described above to be highly satisfactory for the purpose.

It will be seen that the high voltage conductors are fully insulated in the material of the base, while the electrodes are protected by air gaps and enclosed within both the refractory inner shell 58 and the outer shell 59, so that the operator is fully protected against electrical shock. However, as a further safeguard, it is preferred to locate in the upper opening 62 of the inner shell a conducting ring 18, Fig. 8, to which is connected a conducting wire 13 having a coiled spring portion Bi! and extending loosely at its lower end Bl through an opening in the upper base section 3!. Conductor 8| projects sufiiciently below the section to press against the head of one of the screws 56 screwed at its lower end into the metal hub iii of the grounded equipment stand, so as to prevent the occurrence of any high voltage conditions at the top of the inner shell.

The are generated between the electrodes is supplied with a current of air by means of one or more lower openings 82, Figs. 1 and 8, which, when the outer shell is depressed to close the switch, register directly with the air duct 5i between sections 30 and 3! of the base. From this duct a central opening 83 leads through upper base section 3! to a point below and between the electrodes. Additional air for this purpose may enter between the base and the spaced walls of the shell 59 at its lower end.

As appears from the above description of the construction, the outer shell 59 may be slightly depressed by any suitable means, as by downward pressure on an instrument to be heated laid across its upper end. By such downward movement of the shell, the spider 33 is depressed to spring the switch plate into connecting contact with the upper terminals ll of the switch, to bridge the latter and thus close the circuit including the electrodes and the high tension side of the transformer. A sufliciently high voltage is employed, in relation to the gap between the electrodes, as well understood in the art, to immediately create an arc between the electrodes, heating the air and establishing an upward current past the arc and through the upper openings 62 and 53 of the housing. Such upward air current sweeps the arc upwardly to the upper ends of the electrodes and carries a portion of the arc, or at least a volume of air intensely heated thereby, upwardly through the openings, as indicated in Fig. 5, for direct contact with the instrument or material to be heated and located above or across the top of the outer shell. The device is conveniently operated, therefore, by merely a slight downward pressure on the top of the outer shell, as by means of the same hand of the operator which holds the instrument or material to be heated, so as to obviate any special manipulation and it is quickly energized and produces an intense heating action. This efficient action is obtained, furthermore, by a device which is self-contained and compact, occupying the position and substantially the same space as the gas burner which has been commonly employed for such purposes.

Notwithstanding the employment of high voltage current, the construction is such as to fully safeguard the operator against any possibility of shock. The parts of the device are so constructed and arranged that they may be readily and economically manufactured and assembled and as readily detached and separated for cleaning or repair, as may be found desirable from time to time in use. The device is economical in operation since it is energized only during the relatively brief intervals of actual use.

It will thus be seen that the invention accomplishes its objects, and while it has been herein disclosed by reference to the details of a preferred embodiment, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, as it is contemplated that various changes in the construction and arrangement of the parts will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims.

I claim:

1. An electrical heating device comprising a housing having an air passage therethrough provided with. inlet and outlet openings, means movably associated with said housing having a portion located above said outlet opening thereof and formed to receive an article to be heated, spaced electrodes in said housing below said outlet opening thereof, an electrical circuit including said electrodes and a source of high potential current, switch means controlling said circuit, and a connection between said article receiving means and said switch means for actuating said switch means by the movement of said receiving means.

2. An electrical heating device comprising a housing having an air passage therethrough provided with inlet and, outlet openings, means movably associated with said housing having a portion located above said outlet opening thereof formed to receive an article to be heated, spaced electrodes in said housing below said outlet opening thereof, an electrical circuit including said electrodes and a source of high potential current, switch means controlling said circuit, a connection between said article receiving means and switch means, and spring means for raising said receiving means and opening said switch, said switch being closed by the depression of said receiving means by the engagement therewith of an article to be heated.

3. An electrical heating device comprising a housing having an air passage therethrough provided with inlet and outlet openings, means movably associated with said housing having a portion located above said outlet opening thereof and formed to receive an article to be heated, an electrical transformer, spaced electrodes in said housing below said outlet opening, an electrical circuit including said transformer and electrodes, switch means for controlling said circuit, a connection between said article receiving means and switch means, and spring means for raising said receiving means and opening said switch, said switch being closed on depression of said article receiving means by the engagement therewith of an article to be heated.

4. An electrical heating device comprising an inner housing having an air passage therethrough provided with inlet and outlet openings, an outer housing movably associated with and enclosing said inner housing and having a portion located above said outlet opening thereof and formed to receive an article to be heated, an electrical transformer, spaced electrodes inaccessibly enclosed in said inner housing below said outlet opening thereof and connected in the secondary circuit of said transformer, a switch connected in the primary circuit of said transformer, an actuating connection between said outer housing and switch, and spring means for raising said outer housing and opening said switch, said outer housing being depressed to close said switch by the engagement therewith of an article to be heated.

5. An electrical heating device comprising a, housing having a base, an inner refractory shell on the base, an outer shell movably mounted on said base and enclosing and spaced from said inner shell, said shells having registering upper openings therein, spaced electrodes on said base in said inner shell below said openings, an electrical circuit including said electrodes and a source of high potential current, and a switch actuated by the movement of said outer shell for closing said circuit to produce a heating are across said electrodes.

6. An electrical heating device comprising a base of insulating material, an inner refractory shell on said base, an outer shell movably mounted on said base and enclosing and spaced from said inner shell, said shells having registering upper openings therein, spaced electrodes on said base in said inner shell and below said openings, an electrical circuit including said electrodes and a source of high potential current, a switch actuated by the movement of said outer shell for closing said circuit to produce a heating are across said electrodes below said openings and a grounded conducting ring on said inner shell about said opening therein.

7. An electrical heating device comprising a base of insulating material formed by a plurality of separable sections having spaced conductors extending therethrough, an inner shell of refractory material on said base, an outer shell movably mounted on said base and enclosin and spaced from said inner shell, said Shells having upper registering openings therein, spaced electrodes on said base in said inner shell below said upper opening thereof and connected with said conductors, an electrical circuit including said conductors and a source of high potential current, a switch in said base for controlling said circuit and actuated by the movement of said outer shell, said base having a lower opening therein for supplying a current of air to said electrodes and carrying the heat from said are upwardly through said shell openings.

8. An electrical heating device comprising a housing having a base, an inner shell on said base and an outer shell movably mounted on said base and enclosing and spaced from said inner shell, said shells having registering upper openings, an electrical transformer, spaced electrodes inaccessibly enclosed in said inner shell below said openings and connected in the secondary circuit of said transformer, switch means connected in the primary circuit of said transformer, an actuating connection between said outer shell and switch means, and a spring for raising said outer shell and opening said switch, said outer shell being depressed to close said switch by the engagement therewith of an article to be heated at said outlet opening.

9. An electrical heating device comprising a base of insulating material formed by separable upper and lower sections, separable conductors extending therethrough, an inner shell of refractory material on said upper section, an outer shell movably mounted on said base and enclosing said inner shell, said shells having inlet and outlet openings, an electrical transformer having its secondary circuit connected with said conductors, spaced electrodes inaccessibly enclosed in said inner shell and connected with said concluctors, a switch in the primary circuit of said transformer, a connection between said outer shell and said switch, and spring means for raisby engagement therewith of an article to be heated at said outlet opening thereof.

EUGENE R. ZIEGLER. 

